Electro-optical radiation collector for arc flash detection

ABSTRACT

An electro-optical (EO) radiation collector for collecting and/or transmitting EO radiation (which may include EO radiation in the visible wavelengths) for transmission to an EO sensor. The EO radiation collector may be used with an arc flash detection device or other protective system, such as an intelligent electronic device (IED). The arc flash detection device may detect an arc flash event based upon EO radiation collected by and/or transmitted from the EO radiation collector. The EO radiation collector may receive an EO conductor cable, an end of which may be configured to receive EO radiation. A portion of the EO radiation received by the EO radiation collector may be transmitted into the EO conductor cable and transmitted to the arc flash detection device. The EO radiation collector may be adapted to receive a second EO conductor cable, which may be used to provide redundant EO transmission and/or self-test capabilities.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C §119(e) of U.S.Provisional Patent Application Ser. No. 61/098,637, entitled “OpticSensor for Arc Flash Detection,” which was filed Sep. 19, 2008, and ishereby incorporated by reference in its entirety.

TECHNICAL FIELD

This disclosure relates to electro-optical radiation collection and/orsensing devices and, in particular, to a versatile electro-opticalradiation collector that may be used for arc flash detection.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate various exemplary embodiments ofthe present system and method and are a part of the specification.Together with the following description, the drawings demonstrate andexplain the principles of the present system and method. The illustratedembodiments are examples of the present system and method and do notlimit the scope thereof.

FIG. 1A is a block diagram of one embodiment of a system for providingarc flash protection to a power system;

FIG. 1B is a block diagram of another embodiment of a system forproviding arc flash protection to a power system;

FIG. 2 is a block diagram of an arc flash protection device;

FIG. 3 illustrates one embodiment of an electro-optical radiationcollector;

FIG. 4A is an exploded view of another embodiment of an electro-opticalradiation collector;

FIG. 4B is an exploded view of a cap of an electro-optical radiationcollector;

FIG. 5 is a block diagram of one embodiment of an arc flash protectiondevice configured to receive electro-optical radiation collected by anelectro-optical radiation collector;

FIG. 6 is block diagram of another embodiment of an arc flash protectiondevice configured to receive electro-optical radiation collected by oneor more electro-optical radiation collectors; and

FIG. 7 is a block diagram of another embodiment of an arc flashprotection device configured to receive electro-optical radiationcollected by one or more electro-optical radiation collectors.

DETAILED DESCRIPTION

Arc flashes pose a serious risk to both personnel and equipment in thevicinity of a flash. An arc flash may produce intense electro-optical(EO) radiation (including visible light) in the area of the arc. Inaddition, an overcurrent condition may be created on electricconductor(s) that feed the arc.

An arc flash detection unit (AFDU) may be configured to monitor aportion of a power system (e.g., an enclosure, housing, or the like).The AFDU may be configured to detect an arc flash event based onstimulus received from the power system. The AFDU may make use ofvarious different types of stimulus including, but not limited to: EOradiation detected in the vicinity of the power system, current levelswithin the power system, voltage levels at various points within thepower system, heat, chemical detection, pressure differentials (e.g.,sound), detection of particulates within an enclosure, or the like.

The time required to detect an arc flash event by a protection system(e.g., an AFDU) may be used to determine a total time required to clearthe arc flash (e.g., the total time required to clear the arc flash maybe a sum of the time required to detect the flash plus the time requiredto trip protective elements responsive to the detection). The timerequired to clear the arc flash may be referred to as a “total arcingtime,” which may be used to calculate the incident energy released bythe arc flash event (given the arc current, resistance, conductor gap,and the like). The detection time of an arc flash protection system mayvary depending upon the configuration of the protection system (e.g.,the sensitivity of the system). System sensitivity may be selected toprovide a balance between providing adequate arc flash protection andpreventing misoperation (e.g., detecting false positives).

The “Guide for Performing Arc Flash Hazard Calculations,” which ispromulgated by the Institute of Electrical and Electronics Engineers(IEEE) as IEEE 1584, provides several means for calculating arc flashincident energy, one of which is provided below in Equation 1:Log(E _(N))=K ₁ +K ₂+1.0811·Log(I _(a))+0.0011·G  Eq. 1

In Equation 1, E_(N) is the arc flash incident energy, K₁ is aswitchgear-dependent constant value (depending upon whether theswitchgear is in an open or box configuration), K₂ is a constant (0 forungrounded or high-resistance grounded switchgear and −0.113 forgrounded systems), I_(a) is the maximum arcing current, and G is a gapbetween conductors within the switchgear.

The IEEE 1584 standard further provides means for determining anarc-protection boundary as follows:

$\begin{matrix}{D_{b} = \left\lbrack {4.184 \cdot C_{f} \cdot E_{n} \cdot \left( \frac{t}{0.2} \right) \cdot \left( \frac{610^{x}}{E_{b}} \right)} \right\rbrack^{\frac{1}{x}}} & {{Eq}.\mspace{14mu} 2}\end{matrix}$

In Equation 2, D_(b) is the distance of the boundary from the arcingpoint, C_(f) is a voltage constant (1.0 for voltages above 1 kV), E_(n)is the normalized arc flash incident energy (e.g., calculated perEquation 1 above), E_(b) is the incident energy at the boundary (5.0J/cm² for bare skin), and x is a distance exponent constant (0.973 for 5kV switchgear).

The protection boundary may determine where maintenance personnel maysafely work in relation to the switchgear and/or may determine what, ifany, protective gear should be used by the personnel.

Other standards exist for calculating arc flash energy to determineappropriate proximity and/or protective gear requirements. For instance,the National Fire Protection Association (NFPA) provides for thecalculation of an arc thermal performance value (ATPV), which is similarto the IEEE 1584 arc flash incident energy. The ATPV may determine aproximity boundary in which maintenance personnel may safely work. Inaddition, the ATPV and proximity boundary may indicate the nature of theprotective gear that should be used by personnel. Other arc flashsafety-related standards are provided by the National Electric Code(NEC) and Occupational Safety and Health Administration (OSHA).

As used herein, the “electro-optical” (abbreviated herein as EO) mayrefer to electromagnetic and/or optical radiation. EO radiation mayinclude various frequencies and/or wavelengths of electromagnetic and/oroptical radiation, some of which may be emitted during an arc flashevent. EO radiation may include visible light as well as otherwavelengths including, but not limited to: radio, microwave, infrared(IR), ultraviolet (UV), X-ray, and the like. The EO radiation collectorsdisclosed herein may be configured to transmit any single frequency,multiple frequencies, or a predetermined range of frequencies of EOradiation. In some embodiments, EO radiation collectors are tuned orfiltered to gather or transmit only certain frequencies or frequencyranges.

FIG. 1A shows one embodiment of an AFDU 103 in an electrical powersystem 100. The AFDU 103 may be communicatively coupled to portions ofthe power system 100 to receive stimulus 120 therefrom. As will bediscussed below, the AFDU 103 may be configured to detect an arc flashevent occurring within the power system 100 (e.g., within a housing 104)based on the stimulus 120 received from the power system 100 (e.g.,current measurements, EO radiation measurements, etc.).

In some embodiments, the AFDU 103 may be communicatively coupled to oneor more current transformers, or other measurement devices, configuredto provide the AFDU 103 with stimulus 120 comprising currentmeasurements from various points within the power system 100 (e.g., oneither side of a housing 104 in the electrical power system 100). Thehousing 104 may include components that may be susceptible to arc flashevents (e.g., switchgear, circuit breakers, and the like).

The AFDU 103 may be configured to receive other types of stimulus 120,such as measurements of EO radiation detected by one or more EOradiation collectors disposed within the vicinity of the power system100. The EO radiation collectors may be disposed within the housing 104and/or may be positioned to capture EO radiation produced by an arcflash event. In some embodiments, the EO radiation collectors may bepositioned within a switchgear enclosure 105 within the housing 104.

Although particular types of stimulus 120 are discussed herein (e.g.,current and EO stimulus), the AFDU 103 could be configured to detect anarc flash event based on any number of different types of stimulus 120.Therefore, this disclosure should not be read as limited in this regard.

The AFDU 103 may be configured to invoke certain protective functionsupon detecting an arc flash event. The protective function may beinvoked via a communications interface 121 with the power system 100(e.g., with power system components within the housing 104). Forexample, the AFDU 103 may trigger a circuit breaker, a switch, or otherequipment to remove an arcing circuit from power and/or isolate thecircuit from the rest of the power system 100. Alternatively, or inaddition, the AFDU 103 may produce an alarm signal that may be receivedby another protective system (e.g., a protective relay, an IED, or thelike), which may be configured to take one or more protective actionsresponsive to the alarm. The alarm may be transmitted to other remotedevices and/or may be made available for display on a human-machineinterface (HMI). These protective actions may reduce the amount ofenergy released by the arc flash event and/or may alert other systemsand/or personnel to the arc flash event.

FIG. 1B shows an electrical power system 101 that includes anintelligent electronic device (IED) 102 comprising an AFDU 103. The IED102 may provide various monitoring and protection services to the powersystem 101, including electrical power system components within ahousing 104.

As used herein, an IED (such as the IED 102 of FIG. 1) may refer to anyone or combination of: a CPU-based relay and/or protective relay, adigital fault recorder, a phasor measurement unit (PMU), a phasormeasurement and control unit (PMCU), a phasor data concentrator (PDC), awide area control system (WACS), a relay with phasor measurementcapabilities, a wide area protection system (WAPS), a SupervisoryControl and Data Acquisition (SCADA) system, a Programmable AutomationController (PAC), a Programmable Logic Controller (PLC), a dedicated arcflash protection controller (e.g., an AFDU), a system integrityprotection scheme, or any other device capable of monitoring and/orprotecting an electrical power system. Accordingly, the IED 102 maycomprise one or more processors, memories, computer-readable storagemedia, communications interfaces, HMI components, and the like. In theFIG. 1B embodiment, the IED 102 may be a protective relay, such as theSEL 751 manufactured by and available from Schweitzer EngineeringLaboratories, Inc. of Pullman, Wash.

As shown in FIG. 1B, the AFDU 103 may be implemented within the IED 102(e.g., as a component of the IED 102). The AFDU 103 may be implementedas machine-readable and/or machine-interpretable instructions stored ona computer-readable storage media of the IED 102. Alternatively, or inaddition, the AFDU 103 may comprise one or more hardware components. Insome embodiments, the AFDU 103 (or portions thereof) may be implementedindependently of an IED 102 (e.g., the AFDU 103 may comprise its ownindependent processing resources, communications interfaces, etc.).

The IED 102 and/or AFDU 103 may be configured to monitor power systemequipment disposed within the housing 104. The housing 104 may comprisea switchgear cabinet, a sealed enclosure, or any other housing type. Thehousing 104 may enclose switchgear equipment, such as circuit breakers110A, 110B, and/or 110C, and the like.

The AFDU 103 may receive various types of stimulus 120 from the powersystem 101. The stimulus 120 may be received directly (e.g., by sensorscoupled to the AFDU 103) and/or indirectly through another device, suchas the IED 102. In the FIG. 1B example, the AFDU 103 is configured toreceive current stimulus (current measurements obtained by currenttransformers) and EO stimulus (EO radiation collected by EO radiationcollectors). The AFDU 103 may be configured to detect an arc flash eventbased on the current and EO stimulus 120. However, in alternativeembodiments, the AFDU 103 may be configured to detect arc flash eventsusing other stimulus types (e.g., EO radiation and/or currentmeasurements alone, heat, pressure, chemical emissions, etc.).

The AFDU 103 may be configured to monitor a three-phase power signalcomprising three conductors 114A, 114B, and 114C, each of which may runthrough the housing 104 (one for each phase of the three-phase powersignal). For instance, the conductor 114A may carry an “A phase”electrical power signal, the conductor 114B may carry a “B phase”electrical power signal, and the conductor 114C may carry a “C phase”electrical power signal. Although a three-phase power signal is referredto herein, one skilled in the art will recognize that the teachings ofthis disclosure could be applied to power systems comprising any typeand/or number of power signals, and, as such, the teachings of thedisclosure should not be read as limited in this regard.

In the FIG. 1B example, the AFDU 103 receives current measurements fromcurrent transformers (CTs) communicatively and/or electrically coupledto the conductors 114A, 114B, and/or 114C; CTs 112A, 112B, and 112C arecoupled to the conductors 114A, 114B, and 114C at a first location 109,and CTs 108A, 108B, and 108C are coupled to the conductors 114A, 114B,and 114C at a second location 111 (e.g., on an opposite end of thehousing 104).

The AFDU 103 is communicatively coupled to EO radiation collectors 116A,116B, 116C, 116D, and 118, which may be configured to detect EOradiation emitted within the vicinity of the housing 104. As usedherein, an EO radiation collector, such as the point EO radiationcollectors 116A, 116B, 116C, 116D, and/or the loop EO radiationcollector 118, may be configured to capture various types of EOradiation, including visible EO radiation (e.g., visible light),infra-red (IR) radiation, ultra-violet (UV) radiation, and/or EOradiation at other wavelengths. Moreover, as used herein, light or a“light event” may refer to EO radiation that comprises EO energy at manydifferent wavelengths, some of which may be visible to the human eye andsome of which may not. Therefore, this disclosure should not be read aslimited to detection and/or processing of only EO radiation visible tohumans, but should be read as encompassing any type of EO radiationknown in the art.

The EO radiation collectors 116A, 116B, 116C, 116D and 118 may bedistributed within the housing 104 and may be communicatively and/orelectro-optically coupled to the IED 102 and/or AFDU 103. In someembodiments, the EO radiation collectors 116A, 116B, 116C and/or 116Dmay be EO radiation “point collectors,” comprising fiber-optic leads (orother EO conductive material) configured to selectively detect EOradiation within the housing 104 (e.g., detect EO radiation atparticular points and/or locations within the housing 104). The point EOradiation collectors 116A, 116B, 116C, and/or 116D may be placed and/orpositioned within the housing 104 so as to be capable of collecting EOradiation produced by an arc flash event therein (e.g., in the vicinityof the switchgear components, such as the circuit breakers 110A, 110B,and/or 110C, a breaker trunk compartment (not shown), or the like). Forexample, the point EO radiation collectors 116A, 116B, 116C, and/or 116Dmay be positioned to have a line-of-sight and/or an electro-optical pathto respective breakers 110A, 110B, and/or 110C (e.g., to avoid “shadows”or other obscuring structures within the housing 104). In someembodiments, the point EO radiation collectors 116A, 116B, 116C, and/or116D may be optically coupled to additional optical elements (notshown), such as mirrors, fiber-optic leads, lenses, EO conductivematerials, or the like, which may be configured to direct EO radiationproduced within the housing 104 and/or in the vicinity of the switchgearcomponents (e.g., breakers 110A, 110B, and/or 110C) to one or more ofthe point EO radiation collectors 116A, 116B, 116C and/or 116D.

The EO radiation collectors 116A, 116B, 116C, and/or 116D may compriseEO conductive materials, such as fiber-optic filaments, capable ofcollecting EO radiation and transmitting a portion thereof to the IED102 and/or AFDU 103. Alternatively, or in addition, the EO radiationcollectors 116A, 116B, 116C, and/or 116D may be capable of collecting EOradiation and transmitting an electrical signal and/or other indicatorof the detected EO radiation to the IED 102 and/or AFDU 103 (e.g., via acommunication network or the like).

The AFDU 103 may be coupled to other devices capable of collecting EOradiation, such as the loop EO radiation collector 118, which may extendthrough a portion of the housing 104. The loop EO radiation collector118 may comprise one or more sheathed fiber-optic cables (or other EOconductive material), wherein portions of the cable are exposed (e.g.,portions of sheathing around the EO conductive material are removed).The loop EO radiation collector 118 may be configured to receive EOradiation through these exposed portions. The EO radiation so receivedmay be transmitted to the IED 102 and/or AFDU 103. Alternatively, or inaddition, the loop EO radiation collector 118 may comprise a dedicatedEO sensor (not shown), which may transmit an electrical signal or otherindicator of the EO radiation detected thereby (e.g., via acommunication network or the like).

Although FIG. 1B depicts the AFDU 103 receiving EO stimulus from aparticular set of EO radiation collectors 116A, 116B, 116C, 116D, and118, one skilled in the art will recognize that the teachings of thisdisclosure could be applied to any number and/or type of EO radiationcollectors, including, but not limited to: optical lenses, waveguides,concentrators, and the like. Therefore, this disclosure should not beread as limited to any particular number, type, and/or arrangement of EOradiation collectors. Moreover, although a particular housing 104 isdepicted, the disclosure is not limited in this regard; the teachings ofthis disclosure could be applied to any housing known in the artincluding, but not limited to: a breaker box, switch box, busbarenclosure, duct, conduit, or other enclosure or housing type.

The AFDU 103 may be configured to detect an arc flash event based oninter alia stimulus received from the CTs 108A, 108B, 108C, 112A, 112B,and 112C and/or EO radiation collectors 116A, 116B, 116C, 116D, and 118.High levels of EO radiation and/or high current levels may be indicativeof an arc flash event occurring within the housing 104. Responsive tothe AFDU 103 detecting an arc flash event, the IED 102 may be configuredto take one or more protective actions, such as tripping one or morecircuit breakers (e.g., breakers 106A, 106B, and/or 106C), removing oneor more of the conductors 114A, 114B, and/or 114C from power,transmitting one or more alarm signals to external devices, displayingan alarm on an HMI, or the like.

For example, the IED 102 may be communicatively coupled to the circuitbreakers 106A, 106B, 106C via a communication network (e.g., over anEthernet network, a SCADA network, an IEEE C37.118 network, a wirelessnetwork, or the like). Responsive to the AFDU 103 detecting an arc flashevent on one or more of the conductors 114A, 114B, and/or 114C, the IED102 may be configured to interrupt the power flow thereon.

FIG. 2 is one embodiment of an arc flash detection unit (AFDU), such asthe AFDU 103 and/or IED 102 of FIGS. 1A and 1B. An electrical powersystem 200 may be protected by an AFDU 203, which, as discussed above,may be implemented independently and/or in conjunction with an IED (notshown); the AFDU 203 may be part of an IED, such as IED 102 depicted inFIG. 1, and/or may be an independent device (e.g., add-on device), whichmay be communicatively coupled to an IED.

In the FIG. 2 embodiment, the AFDU 203 may monitor a portion of anelectrical power system 200, which may comprise a conductor 215 and acircuit breaker 206. The AFDU 203 may receive various types of stimulus220 from the electrical power system 200. In the FIG. 2 example, theAFDU 203 receives current and EO radiation stimulus 220 via respectivemeasurement devices 213 and 217. A CT 213 may be coupled to theconductor 215 to measure a current flowing thereon. The CT 213 may becommunicatively coupled to an input 211 of the AFDU 203 to providecurrent measurement stimulus thereto. An EO radiation collector 217 maybe placed in proximity to the conductor 215 and/or within a housing 204through which the conductor 215 passes. The EO radiation collector 217may comprise a point-source EO radiation collector, a loop EO radiationcollector, or any other device capable of collecting and/or transmittingEO radiation.

An arc flash event occurring in the vicinity of the conductor 215 (e.g.,between the conductor 215 and ground, another conductor, a switch (notshown), on a circuit breaker (not shown), or the like), may produce anEO event 250. The EO event 250 caused by the arc flash may cause EOradiation to be emitted, which may be collected and/or transmitted bythe EO radiation collector 217. As discussed above, the EO event 250 mayproduce EO radiation at various frequencies and/or wavelengths, some ofwhich may be visible to a human. The EO radiation collector 217 may beelectro-optically coupled to the AFDU 203 to transmit a portion of theEO radiation emitted by the EO event 250 and detected by the EOradiation collector 217 to the EO sensor 221 of the AFDU 203.

The EO sensor 221 may be configured to convert EO radiation receivedfrom the radiation collector 217 into a signal indicative of the EOradiation (e.g., an electrical signal). Accordingly, the EO sensor 221may comprise a photodiode (such as a silicon photodiode), a photoresistor, Charge-Coupled Device (CCD) detector, an IR detector, acomplementary metal-oxide-semiconductor (CMOS) device, or any otherdevice or structure capable of converting EO radiation into anelectrical signal.

In some embodiments, the signal produced by the EO sensor 221 may beamplified by an amplifier 222 and sampled (e.g., converted into adiscrete, digital value) by an A/D converter 223. The amplifier 222 maycomprise a fixed or variable gain amplifier. In alternative embodiments,the amplifier 222 may be omitted. In embodiments implemented usinganalog circuitry, the A/D converter 223 may be omitted.

Although FIG. 2 shows the EO sensor 221, amplifier 222, and A/Dconverter 223 as part of the AFDU 203, one skilled in the art willrecognize that these components could be disposed in proximity to the EOradiation collector 217. In this alternative embodiment, the EOradiation collector 217 may be configured to generate a signalindicative of detected EO radiation (e.g., as a sampled, discretemeasurement) using a local EO sensor, amplifier, and/or A/D converter(not shown), and could communicate the measurement(s) to the AFDU 203via a communication network (not shown) or the like.

The AFDU 203 includes an overlight element 224, which may produce an arclight signal 205 based on the EO measurements received via the EO sensor221. Assertion of the arc light signal 205 may indicate that the AFDU203 has detected EO radiation indicative of an arc flash event.

In some embodiments, the overlight element 224 may compare the sampled,discrete EO radiation measurements produced by the A/D converter 223 toan overlight threshold value. The overlight threshold value mayrepresent an EO radiation level that is indicative of an arc flash event(e.g., as opposed to changes in ambient light conditions or the like).The arc light signal 205 may be asserted if the EO radiation levelexceeds the threshold. The threshold may be adapted according to adesired sensitivity level of the AFDU 203.

The overlight element 224 may implement other comparison techniques. Forexample, the overlight element 224 may implement an inverse timecomparison (inverse time over EO radiation intensity plot), which maycause the arc light signal 205 to assert if the intensity of the EOradiation is maintained above a threshold for a time determined by aninverse time over-EO radiation plot. The time threshold may be basedupon the intensity of the EO radiation; as the intensity of the EOradiation increases, the time required to maintain the EO intensity atthe particular level decreases. Alternatively, or in addition, theoverlight element 224 may comprise an integrator, which may assert thearc light signal 205 if a particular cumulative intensity is achievedwithin a predetermined time period (e.g., within a sliding window).Although various comparison techniques are described herein, theoverlight element 224 is not limited in this regard and could employand/or incorporate any comparison method and/or technique known in theart.

Assertion of the arc light signal 205 may be indicative of an arc flashevent. Therefore, in some embodiments, the arc light signal 205 may betransmitted to an IED (not shown), may cause one or more protectiveactions to take place, such as removing the conductor 215 from the powersystem (e.g., tripping the circuit breaker 206), and/or may be providedas an output of the AFDU 203 (not shown).

In some embodiments, the AFDU 203 may be configured to detect an arcflash event based upon EO and overcurrent stimulus. Accordingly, the arclight signal 205 may flow to an AND gate 228, which may combine the arclight signal 205 with an arc current signal 207. The arc current signal207 may be asserted upon detection of an overcurrent condition(discussed below).

A current input 211 of the AFDU 203 may be configured to receive currentmeasurements acquired by a CT 213 communicatively and/or electricallycoupled to the conductor 215. A filter 225 may filter the currentmeasurements (e.g., using a low-pass filter, a band-pass filter, ananti-alias filter, a combination of filters, or the like). The magnitudeof the current measurements may be calculated by an absolute value block226 and/or sampled (e.g., using an A/D converter (not shown)).

A comparator 227 may use the received current measurements to assert anarc current signal 207. The comparator 227 may implement any comparisontechnique known in the art. In some embodiments, the comparator 227 maycompare the current measurements to a threshold 208. The threshold 208may be an overcurrent threshold indicative of current levels producedduring an arc flash event. Therefore, the arc current signal 207 may beasserted if the current measurements exceed the threshold 208. Thethreshold 208 may be configurable to allow the sensitivity of the AFDU203 to be adjusted.

The AFDU 203 may include other overcurrent comparison mechanisms and/ortechniques. For example, the AFDU 203 may implement an inversetime-over-current comparison, which, as discussed above, may assert thearc current signal 207 if the current measurements exceed a threshold(threshold 208) for a particular time period. The time period may beinversely proportional to the intensity of the current stimulusmeasurements.

The arc light signal 205 and the arc current signal 207 flow to the ANDgate 228, the output of which may comprise an arc flash detection signal209. In some embodiments, the AFDU 203 may further include a securitytimer (not shown). The security timer may supervise the arc flashdetection signal 209, such that the arc flash detection signal 209 isasserted only if the output of the AND gate 228 is asserted for apre-determined time period and/or for a pre-determined number ofmeasurement cycles.

The arc flash detection signal 209 may be used to activate one or moreprotective modules (e.g., protective modules and/or functions of an IED(now shown) upon which the AFDU 203 is implemented). FIG. 2 shows thearc flash detection signal 209 activating a trip signal module 229. Thetrip signal module 229 may comprise a protective function of aprotective device, such as an IED. Assertion of the arc flash detectionsignal 209 may cause the trip signal module 229 to generate a tripsignal to the circuit breaker 206. As discussed above, the arc flashdetection signal 209 may be communicated to an IED or other deviceconfigured to monitor and/or protect the power system 200. Responsive toassertion of the signal 209, the IED may take one or more protectiveactions as described above. The circuit breaker 206 may remove theconductor 215 from power, which may clear the arc flash event andminimize the energy released thereby. The AFDU 203 (alone or inconjunction with another device, such as an IED) may be configured toprovide other arc flash event monitoring and/or protection mechanismsincluding, but not limited to: transmitting the arc flash detectionsignal 209 to an HMI, IED, or other device; tripping additional circuitbreakers; diverting power to or from portions of a power system; and thelike. In some embodiments, the trip signal generator 229 may beconfigured to transmit the arc flash detection signal in a particularformat and/or using a particular protocol, including, but not limitedto: Ethernet, SCADA, IEEE C37.118, SNMP, or the like. As will beappreciated by one of skill in the art, any signaling and/or controlmechanism could be used under the teachings of this disclosure.

In some embodiments, the AFDU 203 may be configured to assert the arcflash detection signal 209 based upon the arc light signal 205 alone(e.g., the arc light signal 205 may flow directly to the trip signalinput 209, bypassing the AND gate 228). Accordingly, the current input211, filter 225, absolute value block 226, comparator 227 and/or ANDgate 228 may be omitted from the AFDU 203.

The EO radiation collector 217, the EO sensor 221, and/or the EOtransmitter/self-test module 219 may be used in connection with any typeof arc flash detection unit configured to detect an arc flash eventusing various different stimulus types (e.g., voltage signals,temperature measurements, chemical readings, pressure measurements,etc.). Therefore, this disclosure should not be read as limited to anyparticular arc flash detection mechanism and/or technique.

As shown in FIG. 2, the EO radiation collector 217 may beelectro-optically coupled to the AFDU 203 by an EO conductor cable 218,which, in some embodiments, may comprise a fiber optic cable. Theoperation and/or configuration of the EO conductor cable 218 and/or theEO radiation collector 217 may be validated by a self-test operationprovided by inter alia an EO transmitter/self-test module 219. In someembodiments, the EO conductor cable 218 may include a plurality of EOconductor cables, including a first conductor and a second conductor.The EO conductor cables 218 may be coupled to the EO radiation collector217 such that there is an optical path therebetween. A first one of theconductors 218 may be coupled to the EO sensor 221, and a second one ofthe conductors 218 may be coupled to an EO transmitter/self-test module219. The EO transmitter/self-test module 219 may be configured toperiodically provide test pulses to the EO radiation collector 217 (viathe second conductor), which may be transmitted to the EO sensor 221 viathe conductor 218 (e.g., the first one of the conductors 218). The EOtransmitter/self-test module 219 may be communicatively coupled to theEO sensor 221 to detect an EO signal responsive to the emitted EOradiation. If an EO signal responsive to the emitting is detected, theEO radiation collector 217 (and EO conductor cable 218) may bevalidated; otherwise, a self-test fail may be detected. Responsive todetection of a self-test failure, the EO transmitter/self-test module219 may cause one or more alarms to be asserted, issue one or morealerts, trip one or more breakers, and/or take other actions.

FIG. 3 depicts one example of an EO radiation collector 300. In the FIG.3 example, the EO radiation collector 300 houses two EO conductorcables, a first EO conductor cable 320 and a second EO conductor cable321. Each of the EO conductor cables 320 and 321 may comprise EOconductors 322 and 323 (e.g., fiber optic cables) within respectivesheaths 324 and 325, which may be opaque to EO radiation (e.g., may benon-electro-optically conductive). As shown in FIG. 3, the sheathing 324and 325 may be removed at respective end portions of the EO cables 320and 321 to expose portions 326 and 327 of the EO conductors 322 and 323.The exposed portions 326 and 327 of the EO conductor cables 320 and 321may allow EO radiation to be received thereby. EO radiation received bythe exposed portions 326 and/or 327 may be transmitted within the EOconductor cables 320 and 321.

The exposed portions 326 and 327 may be secured within the EO radiationcollector 300 at a particular orientation with respect to one another.However, alternative configurations and placements of the EO conductorcables 320 and 321 are possible through modification to the EO radiationcollector 300 (e.g., modifications to the cap 302, the base portion 304,and the like).

In some embodiments, and as illustrated in FIG. 3, the EO conductorcables 320, 322 may be mounted within the EO radiation collector 300,such that the longitudinal axis 328 of the first EO conductor cable 320is non-parallel with respect to the longitudinal axis 329 of the secondEO conductor cable 321. The orientation of the longitudinal axes 328 and329 may provide and/or facilitate EO transmission between the EOconductor cables 320 and 321. The EO transmission path electro-opticallycoupling the EO conductor cables 320 and 322, may allow EO radiationemitted from the first EO conductor cable 320 (via the exposed portion326 thereof) to be received by the second EO conductor cable 321 (viathe exposed portion 327), and vice versa. In some embodiments, and asshown in FIG. 3, the longitudinal axes 328 and 329 may intersect in 2Dor 3D space.

In some embodiments, the EO transmission path between the EO conductorcables 320 and 321 may include the cap 302. Accordingly, the cap 302 maybe configured to transmit EO radiation between the exposed portions 326and 327 of the EO conductor cables 320 and 322. For example, the cap 302may include material configured to diffuse EO radiation. Accordingly, aportion of EO radiation emitted from the exposed end 326 of the first EOconductor cable 320 may be diffused within the cap 302 material andreceived by the exposed end 327 of the second EO conductor cable 321. Insome embodiments, an inner surface of the cap 302 may be treated with areflective material and/or a material having refractive propertiesconfigured to direct EO radiation between the EO conductors 320 and 321.Alternatively, or in addition, the cap 302 may comprise reflectiveportions configured to reflect EO radiation between the portions 326 and327. For example, the cap 302 may include a substantially smooth innersurface (not shown), which may be configured to direct EO radiationbetween the exposed portions 326 and 327 (e.g., a surface proximate tothe exposed ends 326 and 327 of the EO conductor cables 320 and 321).One example of such a surface is described below in conjunction withFIG. 4B.

In some embodiments, the cap 302 may be configured to emit a portion ofEO radiation received via the first and/or second EO conductor cables320 and/or 321. Accordingly, when EO radiation is emitted into the EOradiation collector 300 via the exposed portion 326 of the first EOconductor cable 320 and/or the exposed portion 327 of the second EOconductor cable 321, a portion of the EO radiation may be emitted fromthe cap 302. If the EO radiation is in the visible spectrum, the emittedEO radiation may be visible by a human and/or detected by other EOradiation detection devices. The emission may allow a user (or otherdevice) to confirm that EO radiation has been received by the EOradiation collector 300 (e.g., transmitted to the EO radiation collector300 via the first and/or second EO conductor cable(s) 320 and/or 321).

As shown in FIG. 3, the ends of the exposed portions 326 and 327 may besecured at substantially the same location within in the cap 302 (e.g.,at the same vertical offset within the cap 302). Accordingly, theexposed portions 326 and 327 may both be secured within an EO radiationreceiving area 303 (discussed below).

In some embodiments, the exposed portions 326 and 327 may be in contactwith one another at a contact location 330. The exposed portions 326and/or 327 may be adapted to increase a contact area therebetween. Forexample, ends of the exposed portions 326 and 327 may be adapted (fileddown) to increase the contact area therebetween (e.g., to create acontact plane between the portions 326 and 327 at the location 330).Although not shown in FIG. 3, in some embodiments, the ends of theexposed portions 326 and 327 may be secured in contact using a securingmember, such as a clamping device, a clip, resilient member, adhesives,or the like.

As discussed above, the cap 302 may be formed of materials adapted totransmit EO radiation. Accordingly, incident EO radiation emitted in thevicinity of the EO radiation collector 300 may be transmitted throughthe cap portion 302 and into the exposed portions 326 and 327 of the EOconductor cables 320 and 321.

In some embodiments, the cap 302 may be configured to direct (e.g.,focus) incident EO radiation (e.g., EO radiation emitted in the vicinityof the EO radiation collector) into an EO radiation receiving area 303.For example, the cap 302 may include portions of varying thicknessand/or comprised of materials having different reflective and/orrefractive properties, which may cause incident EO radiation to bedirected to a particular location within the EO radiation collector 300.In the FIG. 3 example, the cap 302 is configured to cause incident EOradiation to be focused into the EO radiation receiving area 303. Thenature (e.g., size, orientation, etc.) of the EO radiation receivingarea 303 may be determined by the configuration of the cap 302 and/orother elements of the EO radiation collector 300 (e.g., additionallenses, surfaces, and the like). As described above, the cap 302 mayinclude materials having differing thicknesses and/or of differingoptical qualities, which may cause EO radiation to be directed todifferent locations within the EO radiation collector 300. In the FIG. 3embodiment, the EO radiation collector 300 is configured to secure bothof the exposed portions 326 and 327 of the EO conductor cables 320 and321 the EO radiation receiving area 303. Accordingly, both the EOconductor cables 320 and 321 may be ideally situated within the EOreceiving area 303 of the EO radiation collector 300 to receive incidentEO radiation collected by the EO radiation collector 300.

In some embodiments, the cap 302 may be configured to diffuse EOradiation. For example, an outer surface of the cap 302 may include aplurality of indentations or dimples, which may cause incident EOradiation to be diffused within the cap 302. The diffusion may beconfigured to distribute incident EO radiation within the cap 302. Thediffusion may allow incident EO radiation received from various anglesand/or locations relative to the EO radiation collector 300 to bereceived at the EO receiving area 303. For instance, incident EOradiation may be diffused within the cap 302 (e.g., by dimples on thesurface of the cap 302 and/or the material comprising the cap 302),which may cause the cap 302 to emit EO radiation, a portion of which maybe transmitted into the EO radiation receiving area 303. In someembodiments, the diffused EO radiation may be directed to the EOreceiving area 303 by adapting the thickness and/or refractiveproperties of the cap 302 material as described above.

FIG. 4A is an exploded view of another embodiment of an EO radiationcollector 400. A cap 402 may be detached from a base portion 404 and amounting portion 450 of the EO radiation collector 400. In the FIG. 4example, the EO conductor cables 420 and 421 are depicted as if securedwithin the EO radiation collector 400. As illustrated, the exposed ends426 and 427 of the EO conductor cables 420 and 421 may be mounted suchthat the longitudinal axes thereof (428 and 429) are non-parallel withrespect to one another. In addition, in some embodiments, thelongitudinal axes 428 and 429 may be intersecting (e.g., on a 2D planeand/or in 3D space).

The manufacture and configuration of an EO radiation collector 400(e.g., the housing 402, base portion 404, and the like) may be accordingto various configurations and materials as are known in the art.According to some embodiments, the cap 402 and the base portion 404 maybe formed from electrically non-conductive materials. The EO radiationcollector 400 may be modified for a particular application in whichspecific materials, sizes, or configurations are desired. The EOradiation collector 400, comprising the base 404 and the cap 402, may bemanufactured as one piece or as two or more separable and/or inseparablepieces.

In some embodiments, the cap 402 may be secured to the base portion 404by a fastening means, such as a weld, adhesive, fusing, snaps, clips,resilient members, cement, zip ties, and/or other fastening means knownin the art. In the FIG. 4 example, the cap 402 includes protruding clips445 configured to mate with clip receivers 440 in the base portion 404.Insertion of the clips 445 into the receiver 440 may secure the cap ontothe base portion 404.

The EO radiation collector 400 may include means for securing one ormore EO conductor cables (e.g., cables 420 and/or 421). The securingmeans may include any means for securing EO conductor cables known inthe art including, but not limited to: adhesives, glue, clips, resilientmembers, gripping members, resilient teeth, clamping mechanisms,clamping members, zip ties, or the like. In the FIG. 4A example, thebase portion 404 includes a gripping member 425 configured to secure theEO conductor cables 420 and 421 within the EO radiation collector 400.The gripping member 425 may comprise a plurality of resilientlydeformable teeth adapted to frictionally engage and secure the EOconductor cables 420 and/or 421. Although not shown in FIG. 4, anadditional member (an independent component and/or formed as part of thebase portion 404 and/or cap portion 402) may be adapted to position theexposed ends 426 and/or 427 in a particular orientation within the EOradiation collector (e.g., provide the bend 430 in the EO conductorcables 420 and 421 depicted in FIG. 4A). The additional member may be aprotrusion, grooves, or any other means for positioning the EO conductorcables 420 and/or 421 in a particular orientation.

The EO collector 400 may include a mounting portion 450 to secure the EOradiation collector 400 onto a particular type of surface (e.g., withina switchgear enclosure or housing). Depending on the desired mountingsurface, a wide variety of conceivable features 450 may be used, such asan adhesive patch, a bolt receiver, one or more clips adapted to bereceived by a clip receiver, or the like.

As illustrated in FIG. 4A, the EO radiation collector 400 may receivetwo EO conductor cables 420 and 421, which may enter the EO radiationcollector 400 from a bottom portion of the cap 402 and/or base portion404. According to alternative embodiments, the EO radiation collector400 may be adapted to receive any number of EO conductor cables ofvarious types. Additionally, the EO radiation collector may be adaptedto receive the EO conductor cables from the sides, top, bottom, and/or acombination thereof. Moreover, means for receiving the EO conductorcables (e.g., the cable entrances and securing means) may be configuredto allow one EO conductor cable to be removed while other cable(s)within the EO radiation collector 400 remain fixedly secured. Aspreviously discussed, according to various embodiments, the plurality ofcables entering the EO radiation collector 400 may be oriented and/orbent, such that the longitudinal axes of each of the cables are notparallel with one another, that the exposed portions of the EO conductorcables are within a receiving area of the EO radiation collector (e.g.,the EO radiation receiving area 303 of FIG. 3), the ends of the exposedportions of the EO conductor cables therein are at substantially thesame height and/or position as one another, and/or EO radiationtransmitted from one of the EO conductor cables may be received by oneor more of the other EO conductor cables and/or emitted from the cap402.

As discussed above, portions of an outer surface 405 of the cap 402 maycomprise indentations and/or dimples configured to diffuse incident EOradiation within the cap 402. The dimples may be adapted to diffuse EOradiation indicative of an arc flash event (e.g., EO radiation having awavelength and/or intensity typically produced in arc flash events). Thedimples may cover the entire outer surface 405 of the cap 402 or only aportion thereof (in a periphery region 406). For example, in someembodiments, the dimples on the cap 402 may be primarily disposed on thesurface of a periphery region 406 of the cap 402. As shown in FIG. 4A,the periphery region 406 may include a top-rear region and/or sideregions of the cap 402. Accordingly, the periphery region 406 mayreceive incident EO radiation emitted from behind and/or the side of theEO radiation collector 400. The incident angle of the EO radiation soreceived may make it difficult to direct the incident EO radiationtowards the exposed ends 426 and 427 of the EO conductor cables 420 and421. The diffusion provided by the dimpling on the surface 405 and/orwithin the periphery region 406 may allow for EO radiation to bereceived by the exposed portions 426 and 427.

FIG. 4B depicts another embodiment of an EO radiation collector cap.FIG. 4B provides a view of an inner portion of the cap 402. As discussedabove, the material comprising the cap 402 may have a thickness profile407 configured to direct incident EO radiation into a receiving area403. As shown in FIG. 4B, the exposed portions 426 and 427 of the EOconductor cables 420 and 421 may both be secured within the EO radiationreceiving area 403.

The EO conductor cables 420 and 421 may be secured at a particularorientation within the cap 402 by an indentation 409 therein. Theindentation 409 (along with the protrusion 413) may be configured tomaintain the EO conductor cables 420 and 421 in the non-parallel-axisorientation described above. In the FIG. 4B example, the EO conductorcables are secured within indentation 409 by clip members 410 and 411.The clip members 410 may be configured to frictionally engage the EOconductor cables 420 and 421 as they enter the cap 402. The clip members411 may be configured to frictionally engage the EO conductor cables 420and 421 to the protrusion 413. The protrusion 413 may be adapted toorient the EO conductor cables 420 and 421 in the non-parallel-axisorientation described above. The cap 402 of FIG. 4B may be secured to abase portion (not shown) by protruding clip members 445.

As discussed above, in some embodiments, the cap 402 may be configuredto diffuse incident EO radiation. The diffusion may be provided by thematerial 407 comprising the cap 402 and/or by features (e.g.,indentations and/or dimples) disposed on an outer surface 405 of the cap402.

In some embodiments, the material 407 from which the cap 402 is formedmay be configured to direct incident EO radiation into the EO receivingarea 403. The incident EO radiation may be directed by adapting thethickness profile of the material 407 and/or selecting differentmaterial configurations (e.g., materials having different refractiveproperties).

As discussed above, EO radiation emitted from one of the EO conductorcables 420 and/or 421 may be received by the other EO conductor cables421 and/or 420. Accordingly, an EO transmission path may exist betweenthe EO conductor cables 420 and 421. The EO transmission path may beprovided by the orientation of the EO conductor cables 420 and 421(e.g., in a non-parallel axis orientation). In some embodiments, EOradiation may be transmitted between the EO conductor cables 420 and 421via the cap 402 (e.g., the cap 402 may provide a portion of the EOtransmission path). In some embodiments, a portion of the inner surfaceof the cap 402 (portion 415) may be configured to be reflective.Accordingly, a portion of EO radiation emitted from the EO conductor 420and/or 421 may be reflected into the other EO conductor 421 and/or 420.The reflective properties of the surface portion 415 may be provided bysmoothing the surface portion 415, depositing a layer of reflectivematerial on the surface portion 415, or the like. Inner side portions417 of the cap may be similarly treated. The reflective treatmentapplied to the inner portion 415 and/or 417 of the cap 402 may beconfigured to allow the portions 415 and/or 417 to transmit incident EOradiation to the exposed portions 426 and 427 (e.g., the reflection maybe substantially one-way, such that incident EO radiation is notreflected out of the cap 402).

FIG. 5 provides an exemplary block diagram of an arc flash detectiondevice having an EO radiation collector. The apparatus 500 may becapable of performing a self-test to validate the proper operationand/or configuration of the EO radiation collectors connected thereto(e.g., the EO radiation collector 513) and/or the electro-opticalconnection between the EO radiation collector 513 and the apparatus 500(e.g., the EO conductor cables 510 and 511).

As shown in FIG. 5, the EO radiation collector 513 may be similar to theEO radiation collectors 300 and/or 400 disclosed above in conjunctionwith FIGS. 3, 4A, and 4B. The apparatus 500 may include an arc flashdetection unit 503, which may be implemented similarly to the AFDU 103and/or 203 disclosed above in conjunction with FIGS. 1A, 1B, and/or 2.The AFDU 503, or portions thereof, may be implemented within an IED 502.Alternatively, the AFDU 503 may be implemented independently of the IED502.

The AFDU 503 and/or IED 502 may be communicatively coupled to the EOradiation collector 513 by EO conductor cables 510 and 511. The EOconductor cables 510 and 511 may include an EO conductor sheathed in anon-EO conductive sheathing. End portions 526 and 527 of the EOconductor cables 510 and 511 may be secured within the EO radiationcollector 513 as described above (e.g., may be secured so that theirlongitudinal axes are non-parallel with respect to one another and/or sothat exposed portions 526 and 527 thereof are within an EO radiationreceiving area). In some embodiments, ends of the EO conductor cables510 and 511 may be in contact.

According to the illustrated embodiment, the IED 502 and/or the AFDU 503may include a processor 541 (which may be a microprocessor, fieldprogrammable gate array (FPGA), application specific integrated circuit(ASIC), or the like) and computer-readable storage media 543 (e.g., diskstorage, optical storage, Flash memory, RAM, or the like). The AFDU 503may use the processor and/or storage media 543 to provide arc flashmonitoring and protection functionality, including self-test. Thecomputer-executable instructions for the self-test functions may bestored within the storage media 543. The self-test may be configured toautomatically operate on a scheduled basis (for example, every fourhours), continuously, and/or operate when a command is received via ahuman-machine interface (not shown), communications link or interface545, or the like.

The orientation of the EO conductor cables 510 and 511 within the EOradiation collector 513 may allow EO radiation to be transmittedtherebetween. Accordingly, EO radiation emitted from the end 526 of theEO conductor cable 510 may be received by the end 527 of the EOconductor cable 511 and vice versa. In some embodiments, the EOradiation collector 513 may be configured to provide an EO transmissionpath between the exposed portions 526 and 527 of the EO conductor cables510 and 511. The EO transmission path may be enabled by the non-parallelorientation of the exposed portions 526 and 527 within the EO radiationcollector 513. For example, a cap 515 (or other components) of the EOradiation collector 513 may be configured to transmit EO radiationbetween the exposed portions 526 and 527 of the EO conductor cables 510and 511. The cap 515 may be comprised of materials configured to refractand/or reflect EO radiation between the cables 510 and 511. In addition,portions of an inner surface of the cap 515 may include reflectiveportions (e.g., the reflective surface 415 and/or 417 of FIG. 4B)configured to reflect EO radiation between the exposed portions 526 and527.

In some embodiments, a self-test may comprise causing an EO emitter 519to emit EO radiation into the first EO conductor cable 510. The EOemitter 519 may comprise any EO radiation source known in the art,including, but not limited to: a flash bulb, a light emitting diode(LED), or the like. If the EO conductor cable 510 is functioningproperly, EO radiation produced by the EO emitter 519 may be transmittedto the EO radiation collector 513 by the EO conductor cable 510. The EOradiation may be emitted into the EO radiation collector 513 via theexposed portion 526 of the EO conductor cable 510. The EO radiationemitted into the EO radiation collector 513 may be transmitted into thesecond EO conductor cable 511 via the exposed portion 527 (e.g., via theEO transmission path described above).

The EO radiation collector 513 may be configured to emit a portion ofthe received EO radiation, allowing a human observer (or other detectionmeans) to detect the EO radiation received thereby (e.g., to verify thatthe EO conductor cable 510 is capable of transmitting EO radiation intothe EO radiation collector 513).

If the EO radiation collector 513 is operating properly and/or isproperly configured (e.g., the exposed portions 526 and 527 are properlyoriented within the EO radiation collector 513 and the like), EOradiation transmitted into the EO radiation collector 513 via EOconductor cable 510 may be received by the second EO conductor cable 511and transmitted to the EO sensor 521. The EO sensor 521 may beconfigured to convert the received EO radiation into a signal (e.g.current and/or voltage signal), which, as discussed above, may befiltered, amplified, and/or quantized (e.g., by an A/D converter). Theresulting signal may then be received by the AFDU 503 and/or processor541, which may validate the operation and/or configuration of the EOradiation collector 513 and/or the EO conductor cables 510 and 511.

In some embodiments, if an EO signal is emitted from the EO emitter 519,but no EO signal is received by the EO sensor 521 (or the signal isbelow an attenuation threshold), the AFDU 503 and/or IED 502 may detecta self-test failure. In response to detecting a self-test failure, theAFDU 503 and/or the IED 502 may take one or more actions including, butnot limited to: asserting one or more alarms, transmitting one or morealert signals (e.g., via the communications interface 545), tripping oneor more breakers, or the like. The alarms and/or alerts may be presentedon a human-machine interface 560 (e.g., via audio queues, visualindications, or the like).

If EO radiation is detected by the EO sensor 521 (and has an intensityabove a threshold), the AFDU 503 and/or IED 502 may detect a self-testpass. The self-test may further comprise determining an attenuation ofthe EO radiation as it is transmitted through the first EO conductorcable 510, the EO radiation collector 513, and the second EO conductorcable 511. If the attenuation exceeds a threshold, the self-testoperation may fail; otherwise, the self-test may pass. The attenuationmay be displayed on the human-machine interface 560, may be transmittedon a communications interface 545, or the like.

In some embodiments, the AFDU 503 and/or IED 502 may be configured tostop arc flash monitoring during a self-test operation. Alternatively,or in addition, the AFDU 503 and/or the IED 502 may be configured todistinguish between EO radiation received as part of a self-testoperation and EO radiation indicative of an arc flash event. Forinstance, in some embodiments, the AFDU 503 and/or the IED 502 may beconfigured to cause the EO emitter 519 to emit EO radiation according toa particular pattern. The pattern may comprise a low-correlation codedsignal or waveform. During a self-test operation, the EO sensor 521 mayreceive return signals indicative of the coded signal. Accordingly, theAFDU 503 and/or IED 502 may be capable of distinguishing between EOradiation indicative of an arc flash event and EO radiation received aspart of a self-test, which may allow the apparatus 500 to performself-testing while simultaneously providing arc flash monitoring and/orprotection. The simultaneous self-test and/or monitoring may be providedindependently of the nature of the EO radiation emitted by the EOemitter 519. Accordingly, the EO radiation pattern emitted by the EOemitter 519 may be of the same wavelength, frequency, and/or intensityas would be produced in an arc flash event. As such, the self-test maybe capable of validating the EO radiation collector 513 and/or EOconductor cables 510 and 511 within the parameters (e.g., frequency,wavelength, and/or intensity) of an actual arc-flash event.Alternatively, or in addition, the EO emitter 519 may be configured toemit EO radiation of a different frequency and/or wavelength than thatproduced during an arc flash event. The resulting EO signals may bedistinguished by the AFDU 503 and/or IED 502 to prevent false arc flashdetections.

In some embodiments, a self-test operation may determine where aself-test failure has occurred (or reduce the search space for thefailure point). As discussed above, the EO radiation collector 513 maybe configured to emit EO radiation received via an EO cable 510 and/or511 (e.g., via the cap 515). An additional sensing device (not shown),such as a human observer (or additional EO radiation collector (notshown)) may be placed within an EO path of the EO radiation collector513 to detect EO radiation emitted thereby. If, during a self-test, EOradiation is detected from the EO radiation collector 513, but no returnsignal is received via the EO conductor cable 511, the IED 502 and/orAFDU 503 may determine that the EO conductor cable used to transmit theEO signal to the EO radiation collector 513 (e.g., EO conductor cable510) is operable, but that a fault exists within the EO radiationcollector 513 and/or in the EO conductor cable 511. The self-test mayswitch the EO conductor cables and re-run the self-test (e.g., connectthe EO emitter 519 to the EO conductor cable 511 and the EO sensor 521to the EO conductor cable 510). The switch may be made via an EOswitching device (not shown), modification of physical connections, orthe like. If, after the switch, the EO radiation collector 513 emits EOradiation during the self-test, the fault may be determined to be in theEO radiation collector itself 513 (since the other EO conductor cable,cable 511, has transmitted EO radiation to the EO radiation collector513). If the EO radiation collector 513 does not emit EO radiation afterthe switch, the fault may be determined to be in the EO conductor cable511. Although a particular self-test scenario is described herein, thedisclosure is not limited in this regard. The AFDU 503 and/or the IED502 may be configured to perform any self-test and/or adaptive self-testknown in the art.

The status of the self-test operations performed by the IED 502 and/orAFDU 503 may be displayed on an HMI 560 and/or communicated via acommunications interface 545. Alternatively, or in addition, the resultsof the self-test operations may be stored on the computer-readablestorage media 543. The results may be made available to personnel viathe HMI 560 or other interface (e.g., interface 545). The display and/orresults of the self-test may include the attenuation (if any) observedduring the test (e.g., a difference between the intensity of EOradiation transmitted into the EO radiation collector 513 versus theintensity of the EO radiation received by the EO sensor 521), theresponse time of the AFDU 503 and/or IED 502 to detect the returnsignal, a probable location of the failure (if any), or the like.

As discussed above, EO radiation transmitted into the EO radiationcollector 513 (e.g., via the EO conductor cable 510) may illuminateportions of the collector 513, such as the cap 515. The illumination maybe used for diagnostics, testing, and/or maintenance of the system 500.For instance, in some embodiments, the AFDU 503 and/or IED 502 may beconfigured to emit visible EO radiation into the EO radiation collector513 responsive to detecting EO radiation at a particular thresholdtherefrom. The threshold may be selected to exceed the ambient EOradiation levels to which the EO radiation collector 513 is typicallyexposed. In some embodiments, the threshold may include an upper boundto prevent the EO emitter 519 from operating during an arc flash event.The emitted EO radiation may illuminate the EO radiation collector 513,thereby providing a visual confirmation that the EO radiation collector513 is operating properly (e.g., is capable of collecting EO radiation,transmitting the collected EO radiation to the EO sensor 521, andreceiving EO radiation from the EO emitter 519).

In one example, an EO radiation emitter 580 may be used to emit EOradiation into the EO radiation collector 513. The EO radiation emitter580 may comprise a flashlight, an LED, flashbulb, incandescent lightsource, fluorescent light source, or any other device capable ofemitting EO radiation. The EO radiation emitter 580 may be operated by ahuman, by the ADFU 503 and/or IDE 502, and/or some other device (e.g., adedicated testing and validation device (not shown)). As discussedabove, a portion of the EO radiation emitted by the EO radiation emitter580 may be collected by the EO radiation collector 513 and transmittedto the EO sensor 521 via the EO conductor cable 511. Responsive todetecting the EO radiation, the AFDU 503 and/or IED 502 may cause the EOemitter 519 to emit visible EO radiation into the EO conductor cable510. The emitted EO radiation may illuminate the EO radiation collector513 with visible light, which may provide a visual confirmation that theEO radiation collector 513 is functioning properly (e.g., the EOradiation collector 513 may “glow” red). In some embodiments, the EOradiation emitter 580 may further include an EO sensor (not shown),which may provide for automated detection of EO radiation emitted fromthe EO radiation collector 513.

FIG. 6 illustrates one embodiment of a system 600 comprising a pluralityof electro-optically coupled EO radiation collectors 602, 604, 606, 608.The EO radiation collectors 602, 604, 606, and 608 may beelectro-optically coupled to an IED 502 and/or AFDU 503.

The EO radiation collectors 602, 604, 606, and 608 may beelectro-optically connected in a series arrangement (daisy chain) usingEO transmission cables 610, 612, 614, 616, and 618. Although a daisychain arrangement is shown herein, the disclosure is not limited in thisregard. In other embodiments, EO radiation collectors (such as the EOradiation collectors 602, 604, 606, and/or 608) could be arranged in aweb pattern, a branching arrangement, in a graph, or other formation.The alternative configurations may include the use of more than two EOconductor cables in a particular EO radiation collector, the use ofbranching EO conductor cables, EO radiation repeaters, or the like.

In the FIG. 6 example, the EO conductor cable 610 is in electro-opticalcommunication with an EO emitter 519 and the EO radiation collector 602.The EO conductor cable 612 electro-optically connects the EO radiationcollector 602 to the EO radiation collector 604, which iselectro-optically coupled to the EO radiation collector 606 by the EOconductor cable 614, which is electro-optically coupled to the EOconductor 608 via the EO conductor cable 616. The EO radiation collector608 is electro-optically coupled to the EO sensor 521 via the EOconductor cable 618.

The EO radiation collectors 602, 604, 606, and/or 608 may be configuredto provide an EO transmission path between the EO conductor cablesreceived therein (e.g., the EO conductor cables 610 and 612 may beelectro-optically coupled within the EO radiation collector 602, the EOconductor cables 612 and 612 may be electro-optically coupled within theEO radiation collector 604, and so on). As described above, thetransmission of EO radiation between the EO conductor cables within theEO radiation collectors 602, 604, 606, and/or 608 may be enabled by anorientation in which the EO conductors are secured therein (non-parallellongitudinal axis orientation), by the configuration of the EO radiationcollectors 602, 604, 606, and/or 608 (e.g., properties of a cap portionof the EO radiation collectors 602, 604, 606, and/or 608), and the like.

In a self-test operation, EO radiation emitted by the EO emitter 519 maybe transmitted into the EO conductor cable 610 to be received at the EOradiation collector 602. The EO radiation received at the EO radiationcollector 602 may be transmitted into the EO conductor cable 612 (viathe EO transmission path provided by the EO radiation collector 602) tothe EO radiation collector 604, which, in turn, may be transmitted tothe EO radiation collectors 606 and 608 as described above. The emittedEO radiation received at the EO radiation collector 608 may betransmitted to the EO sensor 521 via the EO conductor cable 618. The EOsensor 521 may detect the emitted EO radiation returning from the EOradiation collector 608. The AFDU 503 and/or IED 502 may use thedetected EO radiation corresponding to the emitted EO radiation todetermine a result of the self-test operation. If EO radiationcorresponding to the emitted EO radiation is received by the EO sensor521 (and has not been attenuated beyond a threshold), the self-testoperation may pass. If no EO radiation is returned and/or if thereturning EO radiation has been attenuated more than a threshold amount,the result of the self-test operation may be a failure.

The location of a self-test failure may be isolated by detecting EOradiation emitted from the EO radiation collectors 602, 604, 606, and/or608 during a self-test operation. As discussed above, the EO radiationcollectors disclosed herein may be configured to emit EO radiation whenEO radiation is received via an EO conductor cable (e.g., emitted from acap of the EO radiation collector). During a self-test, EO radiation maybe emitted from each of the EO radiation collectors 602, 604, 606,and/or 608 that the emitted EO radiation has reached. If EO radiationdoes not reach a particular EO radiation collector (602, 504, 606, or608), a location of the fault preventing EO radiation from reaching thecollector may be isolated. For example, if emitted EO radiationilluminates the EO radiation collectors 602 and 604, but not 606 or 608,it may be determined that a fault exists in the EO radiation collector604 and/or in the EO conductor cable 614, since the fault presumablydoes not exist in the EO conductor cables 610 and/or 602 since the EOradiation collectors 602 and 604 are receiving the emitted EO radiation.

In some embodiments, a second set of one or more EO radiation collectors(not shown) may be configured to receive EO radiation emitted from theEO radiation collectors 602, 604, 606, and/or 608. The EO radiationdetected by the second set of EO radiation collectors may be used toisolate the location of the cause of a self-test failure. In someembodiments, the second set of EO radiation collectors may be configuredto determine an attenuation of the emitted EO radiation signal as itflows between the EO radiation collectors 602, 604, 606, and/or 608. Thelocation of the cause of a self-test failure may correspond tohigh-levels of attenuation (e.g., high-level of attenuation may existbetween the EO radiation collectors 602 and 604, which may indicate thatthe EO conductor cable 612 is not operating properly).

Alternatively, or in addition, a technician (or other human) may observethe EO radiation emitted from the EO radiation collectors 602, 604, 606,and/or 608 during a self-test operation to visually identify a probablelocation of the cause of a self-test failure. As discussed above, theAFDU 503 and/or IED 502 may be configured to cause the EO emitter 519 toilluminate the EO radiation collectors 602, 604, 606, and/or 608responsive to detecting EO radiation at the EO sensor 521 (e.g., from aflashlight or other EO radiation emitter (not shown)). The illuminationmay provide a visual confirmation that the EO radiation collectors 602,604, 606, and/or 608 are functioning properly.

FIG. 7 depicts another example of a device for detecting an arc flashevent using an EO radiation collector. In the example 700, the AFDU 503and/or IED 503 includes an EO switch component 770, which may beconfigured to selectively, electro-optically couple the EO conductor 610to the EO emitter 519 and/or the EO sensor 521. The EO switch 770 may beconfigured to electro-optically couple to the EO emitter 519 to the EOconductor 610 during a self-test operation. When so configured, the EOconductor 610 may receive EO radiation emitted by the EO emitter 519.When self-testing is not being performed, the EO switch 770 may beconfigured to electro-optically couple the EO conductor 610 to the EOsensor 521. In this configuration, EO radiation collected by the EOradiation collectors 602, 604, 606, and/or 608 and transmitted throughthe EO conductors (612 and/or 614) may be received by the EO sensor 521via the EO conductor 610. As such, EO radiation indicative of an arcflash event may be received by the EO sensor 521 via redundantelectro-optical paths. Accordingly, even if one or more of the EOconductor cables 612, 614, and/or 618 fails (is incapable oftransmitting EO radiation), EO radiation may be received via thealternative path provided by the electro-optical coupling of the EOconductor cable 610 to the EO sensor 521.

In alternative embodiments, the EO switch 770 may be replaced by otherelectro-optical elements, such as splitters, electro-optical elementsconfigured to transmit EO radiation into the EO conductor 610 whileisolating the EO sensor 521 from the emitted EO radiation, or the like.Accordingly, the disclosure should not be read as limited to the use ofany particular EO switching element or mechanism.

In some embodiments, an additional EO switching element (not shown) maybe provided between the EO sensor 521 and the EO conductor cable 618.The additional switching element may be used to direct EO radiationemitted by the EO emitter 519 into the EO conductor 618, which may allowthe “order” of a self-test operation to be reversed (e.g., reverse theflow of EO radiation through the collectors 602, 604, 606 and/or 608during a self-test operation). As discussed above, reversing the flow ofa self-test operation may be used to isolate the cause of a self-testfailure.

In another variation, the EO emitter 519 and EO sensor 521 elements maybe replaced by an EO transceiver element, which may be electro-opticallycoupled to both the EO conductors 610 and 618. The EO transceiver may beconfigured to emit and sense EO radiation on either of the EO conductorcables 610 and/or 618.

Although the AFDU 503 and IED 502 is depicted as electro-opticallycoupled to a plurality of EO radiation collectors 602, 604, 606, and 608in a daisy chain arrangement, the example 700 could be modified toinclude only a single EO radiation collector, incorporate EO radiationcollectors of different types (e.g., loop EO radiation collectors),arrange the EO radiation collectors in different configurations, or thelike.

Additionally, in alternative embodiments of the example 700 (or theexamples 500 and/or 600 described above), the EO radiation collectors602, 604, 606, and/or 608 could be modified to include one or more EOradiation amplifiers, EO radiation repeaters, EO sensors, and the like.In this way, the effects of EO radiation attenuation within the daisychain configuration (or on a long run of an EO conductor cable) could bemitigated and/or obviated.

The above description provides numerous specific details for a thoroughunderstanding of the embodiments described herein. However, those ofskill in the art will recognize that one or more of the specific detailsmay be omitted, or other methods, components, or materials may be used.In some cases, operations are not shown or described in detail.

Furthermore, the described features, operations, or characteristics maybe combined in any suitable manner in one or more embodiments. It willalso be readily understood that the order of the steps or actions of themethods described in connection with the embodiments disclosed may bechanged as would be apparent to those skilled in the art. Thus, anyorder in the drawings or Detailed Description is for illustrativepurposes only and is not meant to imply a required order, unlessspecified to require an order.

Embodiments may include various steps, which may be embodied inmachine-executable instructions to be executed by a general-purpose orspecial-purpose computer (or other electronic device). Alternatively,the steps may be performed by hardware components that include specificlogic for performing the steps, or by a combination of hardware,software, and/or firmware.

Embodiments may also be provided as a computer program product includinga computer-readable storage medium having stored instructions thereonthat may be used to program a computer (or other electronic device) toperform processes described herein. The computer-readable storage mediummay include, but is not limited to: hard drives, floppy diskettes,optical disks, CD-ROMs, DVD-ROMs, ROMs, RAMs, EPROMs, EEPROMs, magneticor optical cards, solid-state memory devices, or other types ofmedia/machine-readable storage media suitable for storing electronicinstructions.

As used herein, a software module or component may include any type ofcomputer instruction or computer executable code located within a memorydevice and/or computer-readable storage medium. A software module may,for instance, comprise one or more physical or logical blocks ofcomputer instructions, which may be organized as a routine, program,object, component, data structure, etc., that perform one or more tasksor implements particular abstract data types.

In certain embodiments, a particular software module may comprisedisparate instructions stored in different locations of a memory device,which together implement the described functionality of the module.Indeed, a module may comprise a single instruction or many instructions,and may be distributed over several different code segments, amongdifferent programs, and across several memory devices. Some embodimentsmay be practiced in a distributed computing environment where tasks areperformed by a remote processing device linked through a communicationsnetwork. In a distributed computing environment, software modules may belocated in local and/or remote memory storage devices. In addition, databeing tied or rendered together in a database record may be resident inthe same memory device, or across several memory devices, and may belinked together in fields of a record in a database across a network.

It will be understood by those having skill in the art that many changesmay be made to the details of the above-described embodiments withoutdeparting from the underlying principles of the invention.

What is claimed is:
 1. An electro-optical (EO) radiation collector,comprising: a cap, including: an inner surface, and an outer surface; afirst EO conductor cable having an end thereof configured for receivingEO radiation; and a second EO conductor cable having an end thereofconfigured for receiving EO radiation, wherein the cap is configured tosecure the end of the first EO conductor and the end of the second EOconductor, such that a longitudinal axis of the end of the first EOconductor and a longitudinal axis of the second EO conductor arenon-parallel, and wherein the inner surface comprises a reflectiveportion configured to transmit EO radiation incident on the outersurface through the inner surface to the second EO conductor, andwherein the reflective portion of the inner surface is furtherconfigured to reflect EO radiation within the cap, to the second EOconductor.
 2. The EO radiation collector of claim 1, wherein the cap isconfigured to direct EO radiation into an EO radiation receiving areawithin the cap, and wherein the end of the first EO conductor cableexposed for receiving EO radiation and the end of the second EOconductor cable exposed for receiving EO radiation are disposed withinthe EO radiation receiving area.
 3. The EO radiation collector of claim1, wherein the cap is configured to secure the ends of the first and thesecond EO conductor cables such that the first EO conductor cable is inelectro-optical communication with the second EO conductor cable for EOtransmission between the first and second EO conductor cables.
 4. The EOradiation collector of claim 3, wherein ends of the first and the secondEO conductor cables are secured within the cap in an orientationconfigured to cause a portion of EO radiation emitted from the first EOconductor cable to be transmitted to the EO receiving portion of the endof the second EO conductor cable.
 5. The EO radiation collector of claim3, wherein the cap is configured to transmit EO radiation between thefirst and the second EO conductor cables.
 6. The EO radiation collectorof claim 5, wherein the cap is comprised of an EO conductive materialconfigured to diffuse EO radiation emitted from the first EO conductorcable for reception by the second EO conductor cable.
 7. The EOradiation collector of claim 1, wherein the longitudinal axes of the endof the first and the second EO conductor cables intersect.
 8. The EOradiation collector of claim 1, wherein an end portion of the first EOconductor cable is in contact with an end portion of the second EOconductor cable.
 9. The EO radiation collector of claim 1, wherein thefirst and the second EO conductor cables comprise one or more opticfibers.
 10. The EO radiation collector of claim 1, wherein saidelectro-optical radiation comprises electromagnetic radiation with oneor more wavelengths between about 300 and 800 nanometers.
 11. The EOradiation collector of claim 1, wherein the cap is configured to emit aportion of EO radiation transmitted into the EO radiation collector byone of the first and the second EO conductor cables.
 12. The EOradiation collector of claim 11, wherein the emitted portion of the EOradiation is configured to be visible by a human.
 13. The EO radiationcollector of claim 1, wherein the cap comprises an indentationconfigured to secure the first end of the first EO conductor and thefirst end of the second EO conductor within the cap.
 14. The EOradiation collector of claim 1, further comprising an EO radiationreceiving area, wherein the cap directs the EO radiation incident on theouter surface into the EO radiation receiving area, and wherein theportions of the ends of the first and the second EO conductor cablesexposed for receiving EO radiation are secured within the EO radiationreceiving area.
 15. The EO radiation collector of claim 14, wherein thecap is configured to diffuse incident EO radiation.
 16. The EO radiationcollector of claim 14, wherein an outer surface of the cap comprises aplurality of dimples, and wherein the dimples are configured to diffuseincident EO radiation.
 17. The EO radiation collector of claim 1,further comprising a mounting member configured to facilitate themounting of EO radiation collector to a surface.
 18. The EO radiationcollector of claim 1, further comprising a securing member configured tosecure the ends of the first and the second EO conductor within the EOradiation collector.
 19. An arc flash detection device, comprising: anelectro-optical (EO) radiation collector, comprising: a cap defining anEO receiving area and including an inner surface, a first EO conductorhaving a first end and a second end, and a second EO conductor having afirst end and a second end, the first end exposed to receive EOradiation from the first end of the first EO conductor transmittedwithin the EO receiving area, wherein the cap is configured to securethe first end of the first EO conductor and the first end of the secondEO conductor within the EO receiving area of the cap, wherein the firstend of the second EO conductor includes an exposed surface with at leastone normal vector perpendicular to a longitudinal axis of the second EOconductor, and wherein the inner surface comprises a reflective portionconfigured to pass incident EO radiation into the EO radiation receivingarea through the inner surface, and wherein the reflective portion ofthe inner surface is further configured to reflect EO radiation withinthe cap; and an EO sensor electro-optically coupled to the EO radiationcollector to receive EO radiation collected thereby, wherein the arcflash detection device is configured to detect an arc flash event usingEO radiation received by the EO sensor.
 20. The arc flash detectiondevice of claim 19, wherein the first end of the first EO conductor andthe first end of the second EO conductor are secured within the EOradiation collector such that an longitudinal axis of the first end ofthe first EO conductor is non-parallel with respect to an longitudinalaxis of the first end of the second EO conductor.
 21. The arc flashdetection device of claim 20, wherein the EO radiation collector atleast partially defines an EO transmission path to electro-opticallycouple the first EO conductor and the second EO conductor.
 22. The arcflash detection device of claim 21, wherein the cap at least partiallydefines the EO transmission path.
 23. The arc flash detection device ofclaim 19, wherein the cap transmits EO radiation, and wherein the capdiffuses EO radiation transmitted therein.
 24. The arc flash detectiondevice of claim 23, wherein an outer surface of the cap comprises aplurality of dimples configured to diffuse incident EO radiation. 25.The arc flash detection device of claim 19, further comprising an EOradiation emitter electro-optically coupled to the EO radiationcollector, wherein the EO radiation emitter is configured to emitvisible EO radiation into the EO radiation collector responsive to theEO radiation sensor detecting EO radiation from the EO radiationcollector, and wherein the cap is configured to emit a visible portionof the EO radiation received from the EO radiation emitter.
 26. An arcflash detection device, comprising: a first electro-optical (EO)radiation collector comprising a first cap that includes a first EOradiation receiving area comprising an inner surface, wherein the firstcap is configured to secure a first EO conductor and a second EOconductor within the first EO receiving area, wherein the inner surfaceof the first cap comprises a reflective portion configured to reflect EOradiation between the first and the second EO conductors, wherein thereflective portion of the inner surface is further configured totransmit EO radiation from outside the first EO radiation collector intothe first EO radiation receiving area, and wherein a first end of thesecond EO conductor includes an exposed surface with at least one normalvector perpendicular to a longitudinal axis of the second EO conductor;a second EO radiation collector comprising a second cap that includes asecond EO radiation receiving area and is configured to secure thesecond EO conductor and a third EO conductor within the second EOreceiving area, and wherein the second EO radiation collector isconfigured to provide an EO transmission path within the second cap ofthe second EO radiation collector between the second and the third EOconductors, and to transmit EO radiation from outside the second EOradiation collector into the second EO radiation receiving area; and anEO sensor in electro-optical communication with an end of the third EOconductor, wherein the arc flash detection device is configured todetect an arc flash event using EO radiation collected by the first EOradiation collector and received by the EO sensor via the third EOconductor.
 27. The arc flash detection device of claim 26, wherein theEO sensor is in electro-optical communication with the first EOconductor, and wherein the arc flash detection device is configured todetect an arc flash event using EO radiation collected by the second EOradiation collector and received by the EO sensor via the first EOconductor.
 28. The arc flash detection device of claim 26, furthercomprising an EO emitter electro-optically coupled to the first EOconductor, wherein the arc flash detection device is configured toperform a self-test operation by causing the EO emitter to emit EOradiation into the first EO conductor, to receive EO radiationcorresponding to the emitted EO radiation using the EO sensor via thethird EO conductor, and to determine a result of the self-test operationusing the received EO radiation corresponding to the emitted EOradiation.